This invention relates to a fluid line swivel joint connector having a quick disconnectable coupling for uncoupling and shutting flow of the fluid through the line, and more particularly to a swivel joint connector for mounting in a fuel supply line of a fuel dispensing station, the swivel joint permitting a dispensing nozzle to pivot relative to the fuel line or permitting a first section of the line to pivot relative to another section, and having detachable means which quickly decouples to shut flow communication at the joint when the tensile load at the joint is above a predetermined level. The invention is additionally directed to a detachable coupling wherein the tensile force due to a pulling on the line, and the hydrostatic forces of the fluid within the coupling are resisted independently and are not cummulative in the coupling, whereby the uncoupling occurs solely as a result of excessive tensile load.
It is known in the fuel dispensing art to include a swivel connector at the dispenser/hose interface so that twisting loads applied to the dispenser are not transmitted to the hose resulting in twisting thereof. Such swivels merely permit the dispenser, such as a fuel dispensing nozzle, to be pivoted about one or more axes relative to the axis of the hose, the swivel permitting flow communication means between the hose and the dispensing device.
Additionally, it is known to utilize quick disconnect or breakaway couplings in the fuel line spaced from the dispenser so that if a vehicle is driven away from the fuel dispensing station before the dispensing nozzle is removed from the filler neck of the vehicle, an uncoupling will result, shutting the flow of fuel and preventing the volatile fuel to be spilled due to either a dislodging of the moorings of the fuel dispensing station, breakage of the hose, or other failure of the fuel dispensing system. The prior art has proposed a number of decouplers which are actuated by a tensile force in the line. A frangible or shear pin has been proposed and utilized in a number of devices, one such device being illustrated in U.S. Pat. No. 3,719,194. Additionally, at least one other device utilizes an infrangible decoupler, such as a groove with spring-loaded detent balls retained together by a collar and uncoupled when a tensile force of predetermined amount is applied to the collar, this device being illustrated in U.S. Pat. No. 4,617,975.
In these and the other known quick disconnects the decoupling units are axially or straight flow through devices which are placed in the fuel line generally a short distance from the fuel dispenser. These devices have not been utilized in or attached to the dispensing nozzle since this would subject them to lateral forces resulting in premature uncoupling of the device, thereby creating a substantial nuisance situation.
Additionally another nuisance situation could occur where the device would uncouple resulting from spike line pressure shock forces when the dispensing nozzle is snapped shut. The rapid shutting of flow resulting in such decoupling is known as snap decoupling. Although most of the known decoupling devices perform satisfactorily when subjected to a small number of snap-off tests, after a substantial number of such rapid shut-offs, a breakage of shear pins and the like may occur. To forestall this occurrence the prior art reduced the cross sectional area in the line so as to reduce the pressure shock forces, but this of course reduces the fuel flow and creates a nuisance since the time for dispensing a quantity of fuel is increased.
Another design defect of the prior art decouplers or breakaways results from the cummulative affect of the tensile pull on the fuel line in which the decoupling devices are mounted and the hydrostatic forces produced by the pressurized liquid carried therein. In the known decouplers the hydrostatic forces are exerted axially in the same direction as the tensile forces, and thus so too are the line shock or pressure-spike forces. Since all three forces are exerted in the same direction, the affect is cummulative. Statutory regulations and insurance underwriters dictate the maximum amount of force transmitted to a ground mounted dispensing station. However, with typical hydrostatic pressures a fuel dispensed through conventionally sized fuel lines and subjected to typical momentary line shocks, it may not be possible with conventional systems to provide the decoupling device with a capability of resisting the recommended maximum detachment force set by certification agencies and yet to uncouple below the maximum tensile force permitted to be transmitted to the dispensing station.